The invention relates to a filter device, particularly for filtering the intake air of an internal combustion engine, comprising a housing with an unfiltered air inlet and a clean air outlet, and a substantially cylindrical, replaceable filter insert disposed in the housing such that the filter insert separates the unfiltered air zone of the housing from the clean air zone. The filter insert has at least one end disk provided with an axial seal which interacts with a sealing surface of the housing to form a seal between the unfiltered air zone and the clean air zone.
This type of filter device is known in the art. Typically, the filter element is fastened in the filter device by a clamping bolt, for which fastening elements are provided on the housing. In these known filter elements, it is also possible to fix the filter element in the housing with a cover which is placed on the housing in the axial direction. If the substantially cylindrical filter element must be installed or removed under conditions where space is limited, pulling off or pulling up in axial direction may not be feasible. In these cases, the filter element must be lifted out of the housing, i.e., the housing is sealed with a lid that covers a portion of the lateral surface. After the cover has been opened, the filter element can be lifted out of the housing and a new filter element can be inserted.
One problem with this housing configuration is that axial displacement of the filter element is required to seal the unfiltered air side of the filter from the filtered air side. In prior art filter devices, this axial displacement has required special screwed connections or bayonet catches or special holding fixtures for the filter element.
Accordingly, it is an object of the invention to provide a filter device in which the filter element can easily be installed and removed under limited space conditions.
A further object of the invention is to provide a filter device which assures a simple, yet reliable seal between the unfiltered zone and the filtered air zone.
These and other objects are achieved in accordance with the present invention by providing a filter device comprising a housing with an unfiltered air inlet and a clean air outlet, and a substantially cylindrical, replaceable filter element arranged in the housing, said filter element separating an unfiltered air zone of the housing from a clean air zone, wherein at least one axial end face of the substantially cylindrical filter element is provided with an axial seal element which interacts with a sealing surface of the housing to form a seal between the unfiltered air zone and the clean air zone; said filter device further comprising a clamping wedge which applies a force to the filter element to urge the axial seal element reliably against the sealing surface of the housing.
In accordance with a further aspect of the invention, the object are achieved by providing a filter element for use in a filter device as described above, comprising an annulus of self-supporting, zigzag-folded filter paper or nonwoven filter material provided at axial end faces thereof with thermoplastic end disks, wherein at least one end disk is provided with at least one bracket or projection for engaging a clamping wedge for urging the filter element in an axial direction.
An important feature of the invention is that a clamping wedge is provided, the force of which is applied in such a way that the axial seal of the cylindrical filter element reliably fits against the sealing surface, which is a fixed part of the housing.
According to one embodiment of the invention, this clamping wedge is arranged on the cover. Closing the cover causes the filter element to be urged against the sealing surface, thus sealing the filter element. Opening the cover causes the filter element to be loosened, so that it is easy to remove.
Another embodiment of the invention provides that the clamping wedge can be inserted into a bracket of the filter element. To support the clamping wedge, a support surface or an additional element that is a fixed part of the housing is provided. The clamping wedge is at least partially wedge-shaped so that the force is readily transmitted when the cover is closed or the clamping wedge is inserted.
Another embodiment of the invention provides for an axial guide on the side of the filter element opposite the sealing surface, i.e., the filter element on this side is supported against the housing and is fixed so as to allow for axial tolerances.
One advantage of supporting the filter element in this manner is that the filter medium does not need to absorb any axial clamping forces. In addition, the filter housing itself can be made thinner since it is not tied into the force flux.
According to one embodiment of the invention, the filter element is comprised of a zigzag-folded filter paper or nonwoven filter material, which has a very high dust collection capacity paired with low flow resistance. The end disks of this filter element are made of a thermoplastic material. The filter element can thus be easily disposed of by incineration.
These and other features of preferred embodiments of the invention, in addition to being set forth in the claims, are also disclosed in the specification and/or the drawings, and the individual features each may be implemented in embodiments of the invention either alone or in the form of subcombinations of two or more features and can be applied to other fields of use and may constitute advantageous, separately protectable constructions for which protection is also claimed.